This segment will be about Geometries, Routing Algorithms, Bootstrapping of Structured overlay.
Structured P2P overlay
A network overlay that connects nodes using a particular data structure or protocol to ensure that node lookup or data discovery is determinsitic.
Distributed Hash Table(DHT)x
A DHT that stores (key, value) pairs and is used for data lookups using a key.
Key Based Routing
The principle by which a message is routed to the owner of a key k from node n following the principle that either the node n owns the key or points to a node that is closed to a node that owns k terms of some key space defined by the DHT.
Routing Table
Data Structure, usually a table, at nodes that maintain links to other nodes in the structure.
Churn
Rate of node joins and leaves in a peer-to-peer network.
Basic Features of Structured P2P Networks
One way to understand the structured P2P overlays/networks and to compare various aspects include the geometries or data structures used in overlays, routing algorithms thats are enabled by these data structures, the affects of churn on various geometries, the maintenance of the data structure and the bootstrapping mechanism. These aspects define the behaviour of structured P2P overlays.
Geometries
structured P2P overlays use number of diff geometries to accomodate participating nodes in P2P overlays. The term geometry is reffered to as structure to organize nodes in P2P overlay. The primary goal of these geometries is to enable the deterministic lookup. The cost or performance of lookups in structured P2P overlay is directly related to how nodes are arranged and how the geometry is maintained when new node arrives and when old nodes leave.
Above are the few examples of P2P geometries.
In Figure (a), nodes are organized in such a way that lookups proceed clock-wise in powers of 2. Each nodes know only about certain number of other nodes in the network.
In Figure (b), lookups proceed in powers of 2 but in geometric space.
In Figure (c), node organisation with a high connectivity among nodes. Here lookups are relativly simple and often only take a single overlay hop.
Routing Algorithm
Structured overlay use routing algorithms to locate nodes in an overlay and retrieve data items from them. The routing algorithm defines how a target node is located in the network. This lookup is closely associated with the geometries of the P2P overlay and the connectivity or info stored at each node.
To be Continued ...
